Dust cover for automatic telephone system mechanism



June 28, 1960 B. SMITH 2,943,136

DUST COVER FOR AUTOMATIC TELEPHONE SYSTEM MECHANISM Filed Oct. 1, 1957 2O INVENTOR.

BJORN SMITH ATTY.

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2,943,136 7 DUST/COVER FOR AUTOMATIC TELEPHONE .SYSTEMMECHANISM mom Sa Lombard, n1., assignot to Automatic Electrlc 'Laboratorlea. Inc., a corporation of Delaware Filed 1, 1951, 'Ser. No. esmss 2 Claims. (Cl; 174-52 7 My invention' relates-in general to covers, 'and'mcre "specifically to-an improved dust cover for an automatic telephone switch mechanism or the like.

Automatic switch mechanisms of the vertical and rotary type, for which my improved cover-is primarily designed, comprise a group of control relays, a bank of contacts, and a switch shaft having means for moving it in a vertical and rotary movement to move a set of wipers into engagement with. oner'of the sets of contacts =in -the bank. Such mechanisms, as well as certain relay groups known asnepeaters etc., are mounted onwa back plate and: havev abase plate extending forwardlywfrom I'thei bottomiofthe. back plate and slightly wid'erthan-the back plate. The mechanisms are usually mounted on a rack by means of pins on the rack and =bayonet slots on rearwardly extending side plates of the back plate.

In the past the covers for such switch plates were also provided with backwardly extending sides having bayonet slots therein and were mounted, by means of such slots, on the same pins upon which the switch mechanism was mounted. As the switches are usually mounted quite close together, the edges of two adjacent covers would sometimes bind and cause difficulty in removing or applying the covers.

In order to overcome this difficulty '1 have provided an improved cover having a downwardly bent catch on the upper back edge of the cover which latches over the upper edge of the back plate of the switch mechanism to hold the upper end of the cover in place. I have also provided a spring latch on the front end of the base plate of the mechanism, which snaps into a groove around the lower edge of the cover to hold the cover securely in place when it is applied.

Referring to the accompanying sheet of drawings, I will describe the detailed construction of my improved cover.

Fig. 1 is a side view of the cover shown applied to the back and base plates of a switch mechanism.

Fig. 2 is a view taken from the top of Fig. 1 showing the top plate of the cover and the edge thereof which latches over the top of the back plate.

Fig. 3 is a partial back view taken from the right of Fig. 1.

Fig. 4 is an enlarged side view of the spring catch attached to the base plate of the switch mechanism with only a small part of the cover and base plates shown.

Fig. 5 is an enlarged front view of the spring catch shown in Fig. 4.

Referring now to the drawing I have shown at 1, the usual back plate of the switch mechanism having the two sides thereof turned back as at 2 and 3 to form mounting flanges. Each of the turned back sides 2 and 3 have a pair of bayonet slots such as 4 and 5 by which the mechanism is hung or mounted on pins 24 on a rack or shelf (not shown) of well-known type. There is a metal box 6 attached to the rear side of back plate 1 covering the back of plate 1 to cover the various 'to' form the two parallel sides. of-finger holds one on each side of the semicircular front portion, one of'which is shown at'10. The plate 8 also 2,943,136 Patented June 28, 11960 2 screws and openings by which the switch mechanisms are mounted. The box 6 is secured tothe back of the plate 1 between the backwardly turned edges 2 and 3 and is held by means of the screw 18, shown in Figs. 2 an 3, which is threaded into a hole in plate 1.

Attached by welding or the like to the lower front surface of back plate 1 is the usual base plate 7 extending out at right'angles to the back plate. The base plate 7 is slightly wider than the back plate 1.

The coveris formed of two' majorp'arts, the front and sides formed of a single sheet of thin sheet steel 8, and a top-plate'9 welded thereto to hold the sides of the sheet 8 rigidly'in place. Thesheet 8,-a'sshown, is formed into a semicircular shape at the front and has the'two sidesextending backward from this semicircular portion The-plate 8 has a pair hasa pairof p'arallel reinforcing ribsformed therein at 11 and 12 in a horizontal direction and avertic'al rein- "forcing rib formed therein at 13. Around the lower edge of the plate 8 is another reinforcing element comprising a sheet of metal 14 turned up around the base 25 of the plate'and' welde'd thereto. A groove 15 is formed in this reinforcing element around the' outer surface.

Thetop plate 9 has its outer edge '16 turned downward and this edge is welded or similarly "secured to the upper outer surface of plate 8 to hold the curved front and the parallel sides in their proper shape. At the rear side of plate 9 is a lip 16 formed from an extended part of plate 9. The lip 16 has a groove 17 cut out from the middle to provide space for the head of the screw 18 extending through the metal box 6 on the back plate 1. The lip 16 is also cut in at the sides so that the lip can pass over the back of box 6 and down between the sides 2 and 3 of back plate 1, as shown in Fig. 2. The lip is bent downward as shown in Figs. 1 and 3 so that it holds the upper part of the cover tightly in place.

Attached to the lower front surface of base plate 7 is a wire spring catch 19 secured to plate 7 by means of screw 20 and nut 21 with washer 22 securely holding the two ends of the wire loop which forms the catch. The upper front part of catch 19 has a portion bent inwardly which snaps into the groove 15 when the cover is pushed downward so that the bottom of the cover is also securely held in place against the base plate 7.

It will thus be seen that the cover is placed slightly above its normal position when being applied to its mechanism, and then lowered with lip 16 passing over the top edge of plate and the box 6 at the back thereof, and with the lower front edge of the cover inside of the spring catch 19. As the cover is then lowered, the lip 16 draws the top of the cover tightly against plate 1 and the groove 15 snaps into place under catch 19.

In applying the cover to the base 1, the rear edges 23 are placed against the pins 24 whereby the cover is held securely against the pins 24 by the catch 19 and is retained in position at the upper portion by the lip 16. It should be understood that the pins 24 are supported by guide bars (not shown) carried by a switch mounting rack in a conventional manner. These pins are used to support adjacent switch bases, such as switch base 1, and heretofore have also been used to carry the switch cover.

It should be noted that base plate 7 is formed in a shape similar to that of top plate 9 as shown in Fig. 2 except that it is slightly wider and extends forward a slight distance in front of the cover. Thus the lower edge of the cover rests tightly against the outer upper surface of plate 7 when held in place.

' With this design it will be seen that the'covei" is readily attached to.the switch mechanism and is ,held snugly zontal base extending forward from its lower edge and having its sides turned backward with a pair of bayonet slots in the back edges of each side for mounting the aply; over .the sides of said back plate for a short distance only, so that said bayonet slots are clear thereof andfree ,for engagement with mounting means on the frame,- and clamping means secured to said base plate and engaging a groove in the lower edge of said cover, when the cover is placed onthe plate, for holding the cover removably in place with its lip and sides engaging the top and sides of the back plate respectively.

2. A mounting foran electrical apparatus comprising a vertical back plate having backwardly turned sides with bayonet slots therein for mounting the same, and a'hori zont-al base plate extending forward from the bottom of said back plate, a flat metal box secured to the rear of said back plate between said backwardly turned sides, a cover removably attached to said backplate and horizontal plate formed from a sheet metal plate with a curved front and-two backwardly extending sides and a top plate having a..correspondingly curved front portion with its side and front edges bent over and welded to the top edge of said metal plate, said 'top jplatefhaving" a downwardly bentlip at the back ed'ge'thereofextending back and downward over the top edges'of-said back plate and of said metal box between said backwardly turned sides of said back plate, the backwardly extending sides of said metal plate of the cover fitting snugly over a portion of the backwardly turned sides of said back plate without covering the bayonet slots therein. and' a latch on the-front edge of the horizontal base engaging a groove in the bottom of the cover to removably hold the cover in place when the cover is applied to the back plate to cover the apparatus. 1

j References Cited in the file of this patent I 1' UNITED STATES PATENTS: 1,013,972 Timmis Jan. 9, 1912 1,065,875 Keagy et al. June24, 1913 J 1,156,974. Chapman Oct. 19,1915 1,620,047 Van Valkenburg Mar; 8, 1927 Moyer etzal .l Och-12, d 

